spectre.console/test/Spectre.Console.Analyzer.Tests/SpectreAnalyzerVerifier.cs

namespace Spectre.Console.Analyzer.Tests;

public static class SpectreAnalyzerVerifier<TAnalyzer>
    where TAnalyzer : DiagnosticAnalyzer, new()
{
    public static Task VerifyCodeFixAsync(string source, DiagnosticResult expected, string fixedSource)
        => VerifyCodeFixAsync(source, new[] { expected }, fixedSource);

    private static Task VerifyCodeFixAsync(string source, IEnumerable<DiagnosticResult> expected, string fixedSource)
    {
        // Roslyn fixers always use \r\n for newlines, regardless of OS environment settings, so we normalize
        // the source as it typically comes from multi-line strings with varying newlines.
        if (Environment.NewLine != "\r\n")
        {
            source = source.Replace(Environment.NewLine, "\r\n");
            fixedSource = fixedSource.Replace(Environment.NewLine, "\r\n");
        }

        var test = new Test
        {
            TestCode = source,
            FixedCode = fixedSource,
        };

        test.ExpectedDiagnostics.AddRange(expected);
        return test.RunAsync();
    }

    public static Task VerifyAnalyzerAsync(string source, params DiagnosticResult[] expected)
    {
        var test = new Test
        {
            TestCode = source,
            CompilerDiagnostics = CompilerDiagnostics.All,
        };

        test.ExpectedDiagnostics.AddRange(expected);
        return test.RunAsync();
    }

    // Code fix tests support both analyzer and code fix testing. This test class is derived from the code fix test
    // to avoid the need to maintain duplicate copies of the customization work.
    private class Test : CSharpCodeFixTest<TAnalyzer, EmptyCodeFixProvider, XUnitVerifier>
    {
        public Test()
        {
            ReferenceAssemblies = CodeAnalyzerHelper.CurrentSpectre;
            TestBehaviors |= TestBehaviors.SkipGeneratedCodeCheck;
        }

        protected override IEnumerable<CodeFixProvider> GetCodeFixProviders()
        {
            var analyzer = new TAnalyzer();
            foreach (var provider in CodeFixProviderDiscovery.GetCodeFixProviders(Language))
            {
                if (analyzer.SupportedDiagnostics.Any(diagnostic => provider.FixableDiagnosticIds.Contains(diagnostic.Id)))
                {
                    yield return provider;
                }
            }
        }
    }
}